For a swept transonic wing, the compression wave set up by the sharp leading edge corner at the wing tip tends to pull the wing shock (if present) forward in the wing tip region. For natural-laminar-flow (NLF) applications this limits the extent of laminar flow that can be achieved despite being in a favourable region of the wing in terms of local Reynolds number and loading where boundary layer transition is normally governed by shock location and not boundary layer instability.
Wing section design and wing tip treatment, such as rounding of the wing tip leading edge (a so-called “Kuchemann tip”), softens the compression wave from the wing tip leading edge and slightly improves the spanwise extent of NLF. However, it has so far not been possible to overcome the tip flow physics and improve NLF spanwise extent to a satisfactory level.